33 research outputs found

    Cricket tympanal organ revisited: morphology, development and possible functions of the adult-specific chitin core beneath the anterior tympanal membrane

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    Vertebrates and insects are phylogenetically separated by millions of years but have commonly developed tympanal membranes for efficiently converting airborne sound to mechanical oscillation in hearing. The tympanal organ of the field cricket Gryllus bimaculatus, spanning 200 mu m, is one of the smallest auditory organs among animals. It indirectly links to two tympana in the prothoracic tibia via tracheal vesicles. The anterior tympanal membrane is smaller and thicker than the posterior tympanal membrane and it is thought to have minor function as a sound receiver. Using differential labeling of sensory neurons/surrounding structures and three-dimensional reconstructions, we revealed that a shell-shaped chitin mass and associated tissues are hidden behind the anterior tympanal membrane. The mass, termed the epithelial core, is progressively enlarged by discharge of cylindrical chitin from epithelial cells that start to aggregate immediately after the final molt and it reaches a plateau in size after 6 days. The core, bridging between the anterior tracheal vesicle and the fluid-filled chamber containing sensory neurons, is supported by a taut membrane, suggesting the possibility that anterior displacements of the anterior tracheal vesicle are converted into fluid motion via a lever action of the core. The epithelial core did not exist in tympanal organ homologs of meso- and metathoracic legs or of nymphal legs. Taken together, the findings suggest that the epithelial core, a potential functional homolog to mammalian ossicles, underlies fine sound frequency discrimination required for adult-specific sound communications

    Separate But Interactive Parallel Olfactory Processing Streams Governed by Different Types of GABAergic Feedback Neurons in the Mushroom Body of a Basal Insect

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    The basic organization of the olfactory system has been the subject of extensive studies in vertebrates and invertebrates. In many animals, GABA-ergic neurons inhibit spike activities of higher-order olfactory neurons and help sparsening of their odor representations. In the cockroach, two different types of GABA-immunoreactive interneurons (calyceal giants [CGs]) mainly project to the base and lip regions of the calyces (input areas) of the mushroom body (MB), a second-order olfactory center. The base and lip regions receive axon terminals of two different types of projection neurons, which receive synapses from different classes of olfactory sensory neurons (OSNs), and receive dendrites of different classes of Kenyon cells, MB intrinsic neurons. We performed intracellular recordings from pairs of CGs and MB output neurons (MBONs) of male American cockroaches, the latter receiving synapses from Kenyon cells, and we found that a CG receives excitatory synapses from an MBON and that odor responses of the MBON are changed by current injection into the CG. Such feedback effects, however, were often weak or absent in pairs of neurons that belong to different streams, suggesting parallel organization of the recurrent pathways, although interactions between different streams were also evident. Cross-covariance analysis of the spike activities of CGs and MBONs suggested that odor stimulation produces synchronized spike activities in MBONs and then in CGs. We suggest that there are separate but interactive parallel streams to process odors detected by different OSNs throughout the olfactory processing system in cockroaches

    Less invasive surgical treatment for aortic arch aneurysms in high-risk patients: A comparative study of hybrid thoracic endovascular aortic repair and conventional total arch replacement

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    ObjectiveFor aortic arch aneurysms, conventional total arch replacement has been the standard surgical option. In selected high-risk patients, we have attempted less invasive hybrid procedure involving supra-aortic bypass and endovascular stent-graft placement. We review the early and midterm outcomes to clarify the impact of the hybrid procedure.MethodsBetween October 2007 and December 2010, 27 patients were treated with the hybrid procedure. During the same period, 191 patients underwent elective conventional total arch replacement. On retrospective analysis, the hybrid procedure was feasible in 103 patients (hybrid feasible) and not feasible in 88 patients (hybrid impossible). Patients undergoing the hybrid procedure attained significantly higher additive (11.6 ± 2.2 vs 9.5 ± 2.4, 10.3 ± 2.8, P < .001, P = .044) and logistic (31.1 ± 14.1 vs 18.8 ± 12.6, 23.7 ± 16.0, P < .001, P = .047) European System for Cardiac Operative Risk Evaluation scores than hybrid-feasible and hybrid-impossible groups.ResultsAlthough the patients in the hybrid group had significantly higher risk, the early outcomes including mortality and morbidity were similar among the 3 groups, as were the 2-year survivals during the follow-up period: 85.9% for the hybrid group, 89.6% for the hybrid-feasible group, and 86.7% for the hybrid-impossible group (P = .510, .850, log-rank test). In the hybrid group, 2 patients required reintervention for type I endoleak.ConclusionsThe early and midterm outcomes of the hybrid procedure for aortic arch aneurysms were satisfactory. This procedure has the potential to be an alternative for conventional total arch replacement for high-risk patients

    High frequency Agrobacterium-mediated transformation and plant regeneration via direct shoot formation from leaf explants in Beta vulgaris and Beta maritima

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    Communicated by H. Uchimiya Abstract We have developed a new procedure for Agrobacterium-mediated transformation of plants in the genus Beta using shoot-base as the material for Agrobacterium infection. The frequency of regeneration from shoot bases was analyzed in seven accessions of sugarbeet (Beta vulgaris) and two accessions of B. maritima to select materials suitable for obtaining transformed plants. The frequency of transformation of the chosen accessions using Agrobacterium strain LBA4404 and selection on 150-mg/l kanamycin was found to be higher than that in previously published methods. Genomic DNA analysis and -glucuronidase reporter assays showed that the transgene was inherited and expressed in subsequent generations. In our method, shoot bases are prepared by a simple procedure, and transformation does not involve the callus phase, thus minimizing the occurrence of somaclonal variations
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